Mechanical seal

ABSTRACT

A mechanical seal includes rotating seal ring which rotate with a rotary shaft, stationary seal rings, and an adaptor which holds the stationary seal rings, the adaptor being fixed to a seal cover by bolts. The mechanical seal further includes a plurality of holders brought into contact with the adapter and provided with through holes. A body part of each of the bolts passes through each of the through holes and is screwed into each of threaded holes formed in the seal cover. The plurality of holders being arranged so as to surround the rotary shaft.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent application Ser. No. 16/982,026, filed Sep. 17, 2020, which in turn is a 371 filing based on PCT International Patent Application Serial No. PCT/JP2019/014573, filed Apr. 2, 2019, the contents of which are incorporated herein.

TECHNICAL FIELD

The present invention relates to a mechanical seal, and more particularly to a mechanical seal in which an adapter is fixed to a seal cover by bolts.

BACKGROUND ART

Conventionally, in a mechanical seal provided between a rotary shaft of rotating equipment such as a pump and a compressor, and a seal cover, a stationary seal ring is biased against a rotating seal ring fixed to the rotary shaft by biasing means to rotate sealing surfaces of the rotating seal ring and the stationary seal ring relatively to each other in close contact with each other, so that a sealed fluid is sealed. In addition, an adapter is used to fix the stationary seal ring to the seal cover, and with the stationary seal ring held by the adapter, the adapter is inserted into a recess in the seal cover in an axial direction to be fixed, facilitating assembling.

For example, in a mechanical seal described in Patent Citation 1, with an adapter having an O-ring attached at the outer periphery inserted into a recess of a seal cover in an axial direction, an annular thin plate is in contact with a side end of the adapter and a side end of the seal cover. Bolts with head parts extend in through holes of the annular thin plate, and are screwed into internally threaded portions extending in an axial direction of the seal cover to fix the annular thin plate to the seal cover, so that the adapter is positioned and fixed in the axial direction. However, since only the O-ring is interposed between an inner periphery of the seal cover and an outer periphery of the adapter, the adapter is likely to rotate relative to the seal cover, reducing the sealing performance.

Meanwhile, in a mechanical seal described in Patent Citation 2, after an O-ring is attached at an side end of a recess of a seal cover, with an adapter having an O-ring attached at the outer periphery inserted into the recess in the seal cover in an axial direction, flat head screws are screwed into the internally threaded portions extending in an axial direction of the seal cover, and the adapter is pushed in the axial direction by head parts of the flat head screws to be positioned and fixed with the O-ring at the side end of the recess in the seal cover in a collapsed state, increasing the sealing performance between the seal cover and the adapter while preventing the rotation of the adapter.

CITATION LIST Patent Literature

-   Patent Citation 1: JP 4684421 B (page 4, FIGS. 1 to 4) -   Patent Citation 2: JP 6196727 B (page 4, FIG. 2.

SUMMARY OF INVENTION Technical Problem

However, in Patent Citation 2, the flat head screws are configured to be directly in contact with the adapter, and when a torque from the rotary shaft is applied to the adapter, the adapter rotates relative to the seal cover, and the torque is thus transmitted directly to the head parts of the flat head screws which are contact with the adapter. This results in that fact that the flat head screws are likely to be loosened.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a mechanical seal in which a torque is less likely to be transmitted to bolts and which is capable of preventing the bolts from loosening.

Solution to Problem

In order to solve the problems described above, a mechanical seal according to the present invention includes: a rotating seal ring which rotate together with a rotary shaft; a stationary seal ring; an adapter which holds the stationary seal ring, the adapter being fixed to a seal cover by bolts; and a plurality of holders brought into contact with the adapter and provided with through holes, a body part of each of the bolts passing through each of the through holes and being screwed into each of threaded holes formed in the seal cover, the plurality of holders being arranged so as to surround the rotary shaft. According to the aforesaid feature, since the adapter is fixed to the seal cover by the bolts which pass through the through holes of the plurality of holders, the rotation of the adapter relative to the seal cover is prevented. Additionally, even when a torque is applied the adapter, the holder receives the torque, and therefore, the torque is less likely to be transmitted to the bolts, and the bolts can be prevented from loosening.

It may be preferable that the holders have inner flange portions formed around the through holes, bottom portions of head parts of the bolts being brought into contact with the inner flange portions. According to this preferable configuration, since the holders are pressed against and fixed to the seal cover with the inner flange portions interposed between the head parts of the bolts and the seal cover, the positioning accuracy of the holders in the axial direction is improved. and the holders can be firmly fixed to the seal cover.

It may be preferable that contact portions of the holders with the adapter are outer flange portions formed in the holders so as to extend radially outward. According to this preferable configuration, since the adapter is pressed against and fixed to the seal cover by the outer flange portions, the adapter can be firmly fixed to the seal cover.

It may be preferable that the holders are provided with receiving recesses for receiving the head parts of the bolts. According to this preferable configuration, an amount of the head parts of the bolts protruding outward of the holders is small, or the parts can be preventing from protruding outward of the holders.

It may be preferable that the seal cover is provided with receiving recesses for receiving the holders. According to this preferable configuration, an amount of the holders protruding outward of the seal cover is small, or the holders can be prevented from protruding outward of the seal cover.

It may be preferable that each of the holders and each of the receiving recesses in the seal cover are formed in a circular shape as viewed in a screw insertion direction of the bolts and are fitted to each other. According to this preferable configuration, installing and assembling the holders to the receiving recesses in the seal cover can be easily performed.

It may be preferable that each of the holders and each of the receiving recesses in the seal cover are formed in a non-circular shape as viewed in a screw insertion direction of the bolts and are fitted to each other. According to this preferable configuration, even when a torque is applied to the adapter with the holders fitted in the receiving recesses in the seal cover, the torque of the holders is regulated, so that no torque is transmitted to the bolts, and the bolts can be more reliably prevented from being loosening.

It may be preferable that the adapter has portions interposed between radially inner side parts of the outer flange portions and the seal cover, gaps are formed between radially outer side parts of the outer flange portions and the seal cover. According to this preferable configuration, when the bolts are tightened, the pressing force for pressing the adapter between the seal cover and the bolts can be concentrated on the radially inner sides of the outer flange portions of the holders.

It may be preferable that a squeeze packing is provided so as to be at least partially positioned between the holders and the seal cover in the screw insertion direction of the bolts. According to this preferable configuration, since the squeeze packing is compressed in the screw insertion direction of the bolts by the adapter pressed by the holders, the sealing performance is increased.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing a configuration of a mechanical seal according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a configuration for fixing an adapter by holders according to the first embodiment.

FIG. 3 is a plan view showing the configuration for fixing the adapter by the holders according to the first embodiment as viewed from an equipment interior side.

FIGS. 4A and 4B are perspective views showing a configuration of the holders according to the first embodiment, and FIG. 4C is a bottom view showing the same.

FIG. 5 is a view showing a procedure for attaching the adapter by the holders according to the first embodiment.

FIGS. 6A and 6B are bottom views showing configurations of holders according to modifications A and B of the first embodiment, and FIG. 6C is an enlarged sectional view showing a configuration for fixing the adapter by the holders according to the modifications A and B.

FIGS. 7A and 7B are bottom views showing configurations of holders according to modifications C and D of the first embodiment, and FIG. 7C is an enlarged sectional view showing a configuration for fixing the adapter by the holders according to the modifications C and D.

FIGS. 8A and 8B are bottom views showing configurations of holders according to modifications E and F of the first embodiment, and FIG. 8C is an enlarged sectional view showing a configuration for fixing the adapter by the holders according to the modifications E and F.

FIGS. 9A and 9B are bottom views showing configurations of holders according to modifications G and H of the first embodiment, and FIG. 9C is an enlarged sectional view showing a configuration for fixing the adapter by the holders according to the modifications G and H.

FIGS. 10A and 10B are bottom views showing configurations of holders according to modifications I and J of the first embodiment, and FIG. 10C is an enlarged sectional view showing a configuration for fixing the adapter by the holders according to the modifications I and J.

FIGS. 11A and 11B are bottom views showing configurations of holders according to modifications K and M of the first embodiment, and FIG. 11C is an enlarged sectional view showing a configuration for fixing the adapter by the holders according to the modifications K and M.

FIG. 12 is a cross-sectional view showing a configuration of a mechanical seal according to a second embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Modes for implementing a mechanical seal according to the present invention will be described below based on embodiments.

First Embodiment

A mechanical seal according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5 . In the present embodiment, the right side of the drawing will be described as an atmosphere side, and the left side of the drawing will be described as an equipment interior side.

As shown in FIG. 1 , a mechanical seal 1 according to the present embodiment is provided between a rotary shaft 2 of rotating equipment such as a pump and a compressor, and a seal cover 3, and mainly includes annular rotating seal rings 20, 21 fixed to the rotary shaft 2 via a sleeve 4, annular stationary seal rings 30, 31 fixed to the seal cover 3, and an adapter 5. The stationary seal rings 30, 31 are, respectively, biased in an axial direction by metal bellows members 60, 61, so that sliding surfaces 20 a, 21 a of the rotating seal rings 20, 21 and sliding surfaces 30 a, 31 a of the stationary seal rings 30, 31 closely slide with each other to allow a sealed fluid in the interior of the equipment to be sealed. The mechanical seal 1 according to the present embodiment is configured as a so-called double mechanical seal in which the rotating seal ring 20 and the stationary seal ring 30 on the atmosphere side, and the rotating seal ring 21 and the stationary seal ring 31 on the equipment interior side face in opposite directions.

The rotating seal rings 20, 21 and the stationary seal rings 30, 31 are typically formed of a combination of SiC (hard material) or a combination of SiC (as an example of hard material) and carbon (as an example of soft material), but are not limited thereto. Any sliding material is applicable as long as it is used as a sliding material for mechanical seal. Further, the SiC includes a sintered compact with boron, aluminum, carbon or the like as sintering aids, as well as a material composed of two or more phases having different components and compositions, for example, SiC in which graphite particles are dispersed, reaction-sintered SiC composed of SiC and Si, SiC—TiC, SiC—TiN, and the like. As carbon, carbon in which a carbonaceous material and a graphite material are mixed, as well as resin-molded carbon, sintered carbon, and the like, can be used. Other than the sliding materials described above, metal materials, resin materials, surface modification materials (as examples of coating materials), composite materials, and the like are also applicable.

As shown in FIG. 1 , the seal cover 3 is made of stainless steel and is formed in a substantially cylindrical shape. A through hole 3 b, through which the rotary shaft 2 and the sleeve 4 can extend, is formed in the interior of the cylindrical portion 3 a. On the radially inner side of the seal cover 3, a first annular attachment portion 3 g is formed on the atmosphere side, to which one end of the bellows member 60 is fixed, and a second annular attachment portion 3 h is formed on the equipment interior side and radially outer side of the first annular attachment portion 3 g, to which a cylindrical baffle 8 with a flange is attached. Thus, the interior of the seal cover 3 is formed in a stepped shape.

As shown in FIGS. 1 and 2 , in an end face portion 3 c on the equipment interior side of the cylindrical portion 3 a, an annular recess 3 d is provided, which is recessed toward the atmosphere side around the through hole 3 b. On the radially inner side of an axially extending bottom surface of the annular recess 3 d, an annular groove portion 3 e is provided, into which an annular squeeze packing 7 is inserted and fitted. The squeeze packing 7 may be made of an elastic material, and the material may be rubber, resin, graphite or the like. On the radially outer side of the axially extending bottom surface of the annular recess 3 d, that is, on the radially outer side of the annular groove portion 3 e, internally threaded holes 3 f as threaded holes extending in the axial direction toward the atmosphere side are provided. Into the internally threaded holes 3 f, body parts 11 a of bolts 11 for fixing the adapter 5 to the seal cover 3 are screwed.

As shown in FIG. 2 and FIG. 3 , in the end face portion 3 c on the equipment interior side of the cylindrical portion 3 a, receiving recesses 10, that is, so-called counterbore holes, are formed, into which holders 9 are inserted and fitted around the internally threaded holes 3 f. The receiving recesses 10 are each defined by an annular bottom surface portion 10 a continuous radially outward perpendicularly from an opening end of the internally threaded hole 3 f, that is, an equipment interior side end thereof, a first side surface portion 10 b extending toward the equipment interior side from an radially outer side end of the bottom surface portion 10 a, an outer edge surface portion 10 c extending in a direction perpendicular to and continuously from an equipment interior side end of the radially outer side of the first side surface portion 10 b, and a second side surface portion 10 d extending from a radially outer side end of the outer edge surface portion 10 c toward the equipment interior side. Thus, the receiving recesses 10 are configured as stepped cylindrical spaces. Further, the radially inner side of the equipment interior side end of the first side surface portion 10 b on, that is, the side of the through hole 3 b thereof, is continuous perpendicularly to a radially extending bottom surface of the annular recess 3 d on the radially inner side thereof. The four receiving recesses 10 are equiangularly arranged in a circumferential direction of the seal cover 3 together with the four internally threaded holes 3 f (see particularly FIG. 3 ).

As shown in FIG. 1 , the adapter 5 is made of stainless steel, is formed in a cylindrical shape with a flange, and includes a cylindrical portion 5 a and an annular flange portion 5 b extending radially outward at an atmosphere side end of the cylindrical portion 5 a. A through hole 5 c is formed in the interior side of the cylindrical portion 5 a, through which the rotary shaft 2 can extend. On the radially inner side of the adapter 5, an annular attachment portion 5 k is formed on the equipment interior side, to which one end of the bellows member 61 is fixed.

As shown in FIGS. 1 and 2 , in an atmosphere side end of the adapter 5, an attachment portion 5 d having a larger diameter than the cylindrical portion 5 a is provided, and the size of an outer periphery of the attachment portion 5 d is substantially equal to the size of an inner periphery of an opening end of the through hole 3 b of the seal cover 3, that is, an equipment interior side end thereof. Further, in the radially outer portion of the flange portion 5 b, an annular stepped portion 5 h is formed by a first outer peripheral surface 5 e on the atmosphere side, an annular surface portion 5 f on the equipment interior side extending radially inward and continuous perpendicularly from an equipment interior side end of the first outer peripheral surface 5 e, and a second outer peripheral surface 5 g extending from an radially inner side end of the annular surface portion 5 f toward the equipment interior side.

With the attachment portion 5 d of the adapter 5 inserted and fitted into the through hole 3 b of the seal cover 3, an annular surface portion 5 m on the atmosphere side of the flange portion 5 b of the adapter 5 is in contact with the radially extending bottom surface of the annular recess 3 d of the seal cover 3. At this time, the annular step portion 5 h formed on the radially outer portion of the flange portion 5 b of the adapter 5, that is, the first outer peripheral surface 5 e, is configured to be axially continuous with the first side surface portion 10 b of the receiving recess 10 in the seal cover 3. Further, the axial position of the annular surface portion 5 f on the equipment interior side constituting the annular step portion 5 h of the adapter 5 is closer to the equipment interior side by the gap Δ than that of the outer edge surface portion 10 c on the radially outer side constituting the receiving recess 10 in the seal cover 3.

Next, the holders 9 will be described in detail. As shown in FIGS. 1 to 4 , the holders 9 are made of stainless steel and are formed in a cylindrical shape with a flange. The holders 9 each include a cylindrical portion 9 a and an annular flange portion 9 b as an outer flange portion and a contact portion extending radially outward at an equipment interior side end of the cylindrical portion 9 a. At the radially center of a bottom portion 9 c as an inner flange portion on the atmosphere side of the cylindrical portion 9 a, that is, on the side of the seal cover 3 thereof, a through hole 9 d is formed to extend therethrough in the axial direction. Further, the holders 9 are inserted and fitted into the receiving recesses 10 in the seal cover 3, so that with the body parts 11 a of the bolts 11 inserted into the through holes 9 d and with the bolts 11 held, the body parts 11 a of the bolts 11 can be screwed into the internally threaded holes 3 f of the seal cover 3.

The holders 9 each have a receiving recess 9 e formed by the cylindrical portion 9 a and an equipment interior side end surface of the bottom portion 9 c, and the receiving recesses 9 e can receive head parts 11 b of the bolts 11. Further, the diameter of the head parts 11 b of the bolts 11 is larger than the diameter of the body parts 11 a, and the diameter of the receiving recesses 9 e is larger than the diameter of the through holes 9 d. Therefore, with the bolts 11 held by the holders 9, the body parts 11 a of the bolts 11 are screwed into the internally threaded holes 3 f of the seal cover 3, so that atmosphere side end surfaces as bottom portions of the head parts 11 b of the bolts 11 received in the receiving recess 9 e can be axially pressed against equipment interior side end surfaces of the bottom portions 9 c of the holders 9. Although the receiving recesses 9 e of the holders 9 are formed as cylindrical spaces, the shape thereof is not limited to this, and may be freely formed as long as the receiving recesses 9 e can receive the head parts 11 b of the bolts 11.

Further, since the flange portions 9 b of the holders 9 on the radially inner side, that is, on the side of the through hole 3 b extend to axially overlap with the annular stepped portion 5 h of the adapter 5, the annular stepped portion 5 h of the flange portion 5 b of the adapter 5 can be interposed in the axial direction between the radially inner sides of the flange portions 9 b of the holder 9 and the radially extending bottom surface of the annular recess 3 d of the seal cover 3. At this time, the squeeze packing 7 disposed between the bottom portion of the annular recess 3 d of the seal cover 3, that is, the annular groove portion 3 e, and the flange portion 5 b of the adapter 5 is compressed in a screw insertion direction of the bolts 11.

Next, a procedure for assembling the mechanical seal 1 will be described. As shown in FIG. 5 , first, the bellows member 60 and the stationary seal ring 30 are fixed to the first annular attachment portion 3 g of the seal cover 3, and the bellows member 61 and the stationary seal ring 31 are fixed to the annular attachment portion 5 k of the adapter 5. Next, the sleeve 4 is inserted into the through hole 3 b of the seal cover 3 from the equipment interior side, and the sliding surface 20 a of the rotating seal ring 20 fixed to a holding portion 4 a of the sleeve 4 is brought into contact with the sliding surface 30 a of the stationary seal ring 30. The squeeze packing 7 thinly coated with molybdenum disulfide grease is inserted and fitted into the annular groove portion 3 e of the seal cover 3.

Next, the baffle 8 is inserted into a gap between the seal cover 3 and the sleeve 4 from the equipment interior side. At this time, a locking pin 3 m provided in the second annular attachment portion 3 h of the seal cover 3 is fitted into a notch 8 b provided in the flange portion 8 a of the baffle 8 to regulate the rotation of the baffle 8 relative to the seal cover 3.

Next, the attachment portion 5 d of the adapter 5 is inserted and fitted into the through hole 3 b of the seal cover 3, and the sliding surface 31 a of the stationary seal ring 31 fixed to the adapter 5 is brought into contact with the sliding surface 21 a of the rotating seal ring 21 fixed to the holding portion 4 a of the sleeve 4. At this time, a locking pin 5 n provided in the attachment portion 5 d of the adapter 5 is inserted into a notch 8 c provided at an equipment interior side end of the baffle 8 to regulate the rotation of the adapter 5 relative to the seal cover 3.

Finally, the holders 9 are inserted and fitted into the receiving recesses 10 in the seal cover 3 and the annular stepped portion 5 h of the adapter 5, and with the body parts 11 a of the bolts 11 inserted into the through holes 9 d of the holders 9 and with the bolts 11 held by the holders 9, the body parts 11 a of the bolts 11 are screwed into the internally threaded holes 3 f of the cover 3, so that the adapter 5 is fixed to the seal cover 3.

A set ring 12 is externally fitted to an atmosphere side end of the sleeve 4 exposed from the through hole 3 b of the seal cover 3. After assembling the mechanical seal 1, as shown in FIG. 1 , the rotary shaft 2 is inserted into the sleeve 4. The set ring 12 is fastened evenly in the circumferential direction by a plurality of set screws 13, so that the mechanical seal 1 is attached to the rotary shaft 2.

Accordingly, in the mechanical seal 1 according to the present embodiment, since the adapter 5 is fixed to the seal cover 3 by the bolts 11 extending through the through holes 9 d of the plurality of holders 9, the rotation of the adapter 5 relative to the seal cover 3 is prevented. In addition, even when a torque is applied to the adapter 5, the holders 9 receive the torque, so that the torque is less likely to be transmitted to the bolts 11, and the bolts 11 can be prevented from being loosened.

Further, since the holders 9 each have the bottom portion 9 c around the through hole 9 d, which is in contact with the atmosphere side end surface as a bottom portion of the head part 11 b of the bolt 11, with the bottom portions 9 c of the holders 9 interposed between the head parts 11 b of the bolts 11 and the bottom surface portions 10 a of the receiving recesses 10 in the seal cover 3, the holders 9 are pressed against and fixed to the seal cover 3. Therefore, the holders 9 can be firmly fixed to the seal cover 3.

Further, since the flange portion 5 b of the adapter 5 is pressed against and fixed to the annular recess 3 d of the seal cover 3 by the flange portions 9 b of the holder 9 on the radially inner side, that is, on the side of the through hole 3 b, the adapter 5 can be firmly fixed to the seal cover 3. In addition, when the bolts 11 are tightened until the bottom portions 9 c of the holders 9 come into contact with the bottom surface portions 10 a of the receiving recesses 10 in the seal cover 3, the position of the flange portions 9 b of the holders 9 relative to the annular surface portion 5 f on the equipment interior side of the flange portion 5 b of the adapter 5 is the predetermined tightening position, improving the positioning accuracy in the axial direction and facilitating assembling.

Furthermore, while the flange portion 5 b of the adapter 5 is interposed between the radially inner sides of the flange portions 9 b of the holders 9 and the radially extending bottom surface of the annular recess 3 d of the seal cover 3, the axial gap Δ (see FIG. 2 ) is formed between the radially outer sides of the flange portions 9 b of the holders 9 and the outer edge surface portions 10 c of the receiving recesses 10 of the seal cover 3. Therefore, when the bolts 11 are tightened, the pressing force for pressing the holders 9 against the seal cover 3 and pressing the flange portion 5 b of the adapter 5 between the holders 9 and the seal cover 3 can be concentrated on the radially inner sides of the flange portions 9 b of the holders 9. The radially outer sides of the flange portions 9 b of the holders 9 and the outer edge surface portions 10 c of the receiving recesses 10 in the seal cover 3 may be in contact with each other in the axial direction, that is, the gap Δ may not be provided.

Further, since the squeeze packing 7 is arranged between the radially inner sides of the flange portions 9 b of the holders 9 and the bottom portion of the annular recess 3 d of the seal cover 3 in the screw insertion direction of the bolts 11, the squeeze packing 7 is compressed in the screw insertion direction of the bolts 11 by the flange portion 5 b of the adapter 5 which receives the pressing force from the holders 9 when the bolts 11 are tightened, increasing the sealing performance. Thus, it is possible to configure a mechanical seal that seals a high-pressure sealed fluid, such as using the metal bellows members 60 and 61. In addition, since the squeeze packing 7 is interposed between the adapter 5 and the seal cover 3, the friction between the adapter 5 and the seal cover 3 increases, so that the rotation of the adapter 5 relative to the seal cover 3 can be prevented.

Further, since the holders 9 are provided with the receiving recesses 9 e for receiving the head parts 11 b of the bolts 11, the head parts 11 b of the bolts 11 do not protrude outward, that is, on the equipment interior side of the holder 9, so that space saving can be achieved. In addition, the receiving recesses 9 e of the holders 9 may be configured such that the head parts 11 b of the bolts 11 slightly protrude outward, that is, on the equipment interior side of the holders 9.

Further, since the seal cover 3 is provided with the receiving recesses 10 for receiving the holders 9, the holders 9 do not protrude outward of the end face portion 3 c on the equipment interior side of the seal cover 3, so that space saving can be achieved. In addition, the receiving recesses 10 in the seal cover 3 may be configured such that part of the holders 9 slightly protrudes outward, that is, on the equipment interior side of the end face portion 3 c on the equipment interior side of the seal cover 3.

Further, the holders 9 are formed in a circular shape as viewed in the screw insertion direction, and the receiving recesses 10 in the seal cover 3 are formed in a substantially circular shape as viewed in the screw insertion direction, and with the holders 9 inserted and fitted into the receiving recesses 10 in the seal cover 3, the holders 9 are rotatable relative to the cover 3 and the adapter 5. Therefore, even when a torque is applied to the adapter 5, the holders 9 receive the torque to be easily rotated, and the torque is less likely to be transmitted to the bolts 11, so that the bolts 11 can be prevented from loosening. In addition, the holders 9 may be formed, for example, in a polygonal shape as viewed in the screw insertion direction as long as the holders 9 are rotatable while being inserted and fitted into the receiving recesses 10 in the seal cover 3. Furthermore, installing/assembling the holders 9 to the receiving recesses 10 in the seal cover 3 can be easily performed.

Further, since the respective holders 9 are provided in the plurality of receiving recesses 10 provided in the circumferential direction of the seal cover 3, a space in the circumferential direction between the holders 9 is provided, so that heat transfer from the equipment interior side can be prevented, as compared with a conventional annular thin plate continuous in the circumferential direction of the seal cover 3. In addition, since the seal cover 3, the adapter 5, and the holders 9 are made of the same stainless steel, stress due to thermal expansion is less likely to relatively act.

Next, a modification of the holders 9 according to the first embodiment will be described. As a modification A of the holders 9 according to the first embodiment, holders 109 shown in FIG. 6A are formed in a circular shape as viewed in the screw insertion direction without a flange portion extending radially outward. A seal cover 103 has an annular recess 103 b formed up to the radially outer side. An adapter 105 has a flange portion 105 b extending up to the radially outer portion of the annular recess 103 b of the seal cover 103, and receiving recesses 110 are formed by the flange portion 105 b of the adapter 105 and the annular recess 103 b of the seal cover 103. Further, the flange portion 105 b of the adapter 105 has through holes 105 k extending therethrough in the axial direction and formed at positions corresponding to internally threaded holes 103 h of the seal cover 103 (see FIG. 6C).

Further, as a modification B of the holders 9 according to the first embodiment, holders 209 shown in FIG. 6B are formed in a stadium shape as viewed in the screw insertion direction without a flange portion extending radially outward. Further, the holders 209 are cut out at opposite ends in a direction perpendicular to the radial direction of the seal cover 103, and receiving recesses 209 e are formed in a rectangular parallelepiped shape which is open in a direction perpendicular to the radial direction of the seal cover 103. The seal cover and the adapter, to which the holders 209 according to the modification B are applied, have the same configuration as the seal cover 103 and the adapter 105 described above, and thus the description thereof is omitted. In addition, the phrase “cut out” means that it is not necessary to be actually cut out and manufactured and it is only necessary to have a cutout shape. The same applies to the followings.

Accordingly, the holders 109, 209 according to the modifications A, B are formed in a circular shape as viewed in the screw insertion direction and in a stadium shape as viewed in the screw insertion direction, respectively, and the holders 109, 209 are rotatable relative to the seal cover 103 and the adapter 105. Therefore, even when a torque is applied to the adapter 105, the holders 109, 209 receive the torque to be easily rotate, and the torque is less likely to be transmitted to the bolts 11, so that the bolts 11 can be prevented from loosening. In addition, installing/assembling the holders 9 to the receiving recesses 110 in the seal cover 103 can be easily performed.

In addition, as a modification C of the holders 9 according to the first embodiment, holders 309 shown in FIG. 7A are formed in a circular shape in the screw insertion direction, and have respective flange portions 309 b having a substantially semicircular shape formed corresponding to the radially inner side and the radially outer side of the seal cover 303. Receiving recesses 310 in the seal cover 303 are formed in a circular shape as viewed in the screw insertion direction corresponding to the shape of the holders 309 (see FIG. 7C).

Further, as a modification D of the holders 9 according to the first embodiment, holders 409 shown in FIG. 7B are formed in a stadium shape as viewed in the screw insertion direction, and have respective flange portions 409 b having a substantially semicircular shape formed corresponding to the radially inner side and the radially outer side of the seal cover 303. The holders 409 are cut out at opposite ends in a direction perpendicular to the flange portions 409 b, and receiving recesses 409 e are formed in a rectangular parallelepiped shape which is open in a direction perpendicular to the flange portions 409 b. The seal cover, to which the holders 409 according to the modification D are applied, has the same configuration as the seal cover 303 described above, and thus the description thereof is omitted.

Further, as a modification E of the holders 9 according to the first embodiment, holders 509 shown in FIG. 8A are formed in a circular shape as viewed in the screw insertion direction, and flange portions 509 b are formed corresponding to the radially inner side of a seal cover 503. Receiving recesses 510 in the seal cover 503 are formed in a circular shape as viewed in the screw insertion direction corresponding to the shape of the holders 509 (see FIG. 8C).

Further, as a modification F of the holders 9 according to the first embodiment, holders 609 shown in FIG. 8B are formed into a stadium shape as viewed in screw insertion direction, and have respective flange portions 609 b having a substantially semicircular shape formed corresponding to the radially inner side of the seal cover 503. The holders 609 are cut out at opposite ends in a direction perpendicular to the flange portions 609 b, and receiving recesses 609 e are formed in a rectangular parallelepiped shape which is open in a direction perpendicular to the flange portions 609 b. The seal cover, to which the holders 609 according to the modification F are applied, has the same configuration as the seal cover 503 described above, and thus the description thereof is omitted.

Accordingly, the shapes of the holders 309, 409, 509, 609 and the receiving recesses 310, 510 in the seal covers 303, 503 are formed in a circular shape as viewed in the screw insertion direction or in a stadium shape as viewed in the screw insertion direction, and are fitted to each other. Therefore, even when a torque is applied to the adapter 5 with the holders 309, 409, 509, 609 fitted into the receiving recesses 310, 510 in the seal covers 303, 503, the torque of the holders 309, 409, 509, 609 is regulated. Thus, no torque is transmitted to the bolts 11, so that the bolts 11 can be more reliably prevented from loosening. In addition, installing/assembling the holders 309, 409, 509, 609 to the receiving recesses 310, 510 in the seal covers 303, 503 can be easily performed.

Further, as a modification G of the holders 9 according to the first embodiment, holders 709 shown in FIG. 9A are formed in a square as viewed in the screw insertion direction, and respective flange portions 709 b are formed corresponding to the radially inner side and the radially outer side of a seal cover 703. Receiving recesses 710 in the seal cover 703 are formed in a square as viewed in the screw insertion direction corresponding to the shape of the holders 709 (see FIG. 9C).

Further, as a modification H of the holders 9 according to the first embodiment, holders 809 shown in FIG. 9B are formed in a rectangular shape as viewed in the screw insertion direction, and respective flange portions 809 b are formed corresponding to the radially inner side and the radially outer side of the seal cover 703. Receiving recesses 809 e of the holders 809 are formed in a rectangular parallelepiped shape which is open in a direction perpendicular to the flange portions 809 b. The seal cover, to which the holders 809 according to the modification H are applied, has the same configuration as the seal cover 703 described above, and thus the description thereof is omitted.

Further, as a modification I of the holders 9 according to the first embodiment, holders 909 shown in FIG. 10A are formed in a square viewed in the screw insertion direction, and flange portions 909 b is formed corresponding to the radially inner side of a seal cover 903. Receiving recesses 910 in the seal cover 903 are formed in a square viewed in the screw insertion direction corresponding to the shape of the holders 909 (see FIG. 10C).

Further, as a modification J of the holders 9 according to the first embodiment, holders 1009 shown in FIG. 10B are formed in a rectangular shape as viewed in the screw insertion direction, and flange portions 1009 b are formed corresponding to the radially inner side of the seal cover 903. Receiving recesses 1009 e of the holders 1009 are formed in a rectangular parallelepiped shape which is open in a direction perpendicular to the flange portions 1009 b. The seal cover, to which the holders 1009 according to the modification J are applied, has the same configuration as the seal cover 903 described above, and thus the description thereof is omitted. Further, as a modification K of the holders 9 according to the first embodiment, holders 1109 shown in FIG. 11A are formed in a square as viewed in a screw insertion direction without a flange portion extending radially outward. A seal cover 1103 has an annular recess 1103 b formed up to the radially outer side. An adapter 1105 has a flange portion 1105 b extending up to the radially outer side of the annular recess 1103 b of the seal cover 1103, and receiving recesses 1110 are formed by the flange portion 1105 b of the adapter 1105 and the annular recess 1103 b of the seal cover 1103. In addition, the flange portion 1105 b of the adapter 1105 has through holes 1105 k extending therethrough in the axial direction and formed at positions corresponding to internally threaded holes 1103 h of the seal cover 1103 (see FIG. 11C).

Further, as a modification M of the holders 9 according to the first embodiment, holders 1209 shown in FIG. 11B are formed in a rectangular shape as viewed in a screw insertion direction without a flange portion extending radially outward. Receiving recesses 1209 e of the holders 1209 are formed in a rectangular parallelepiped shape which is open in a lateral direction. The seal cover and the adapter, to which the holders 1209 according to the modification M are applied, have the same configuration as the seal cover 1103 and the adapter 1105 described above, and thus the description thereof is omitted.

Accordingly, the holders 709, 809, 909, 1009, 1109, 1209 and the receiving recesses 710, 910, 1110 in the seal covers 703, 903, 1103 are formed in a non-circular shape as viewed in the screw insertion direction and are fitted to each other. Therefore, even when a torque is applied to the adapters 5, 1105 with the holders 709, 809, 909, 1009, 1109, 1209 fitted into the receiving recesses 710, 910, 1110 in the seal covers 703, 903, 1103, the torque of the holders 709, 809, 909, 1009, 1109, 1209 is regulated. Thus, no torque is transmitted to the bolts 11, so that the bolts 11 can be more reliably prevented from loosening. The shape of the holders and the receiving recesses in the seal covers formed in a non-circular shape as viewed in the screw insertion direction has been described as a square shape, however, is not limited to this. They may be formed as a polygon such as a hexagon and an octagon.

Second Embodiment

Next, a mechanical seal according to a second embodiment will be described with reference to FIG. 12 . The same components as those shown in the above embodiment are denoted by the same reference numerals, and redundant description will be omitted.

A mechanical seal 1301 according to the second embodiment will be described. As shown in FIG. 12 , in the present embodiment, the mechanical seal 1301 is provided between the rotary shaft 2 of rotating equipment such as a pump and a compressor, and a seal cover 1303, and mainly includes the annular rotating seal rings 20, 21 fixed to the rotary shaft 2 via a sleeve 1304 and the annular stationary seal rings 30, 31 fixed to the seal cover 1303 and an adapter 1305. The stationary seal rings 30, 31 are, respectively, biased in the axial direction by the metal bellows members 60, 61, so that the sliding surfaces 20 a, 21 a of the rotating seal rings 20, 21 and the sliding surfaces 30 a, 31 a of the stationary seal rings 30, 31 closely slide with each other to allow the sealed fluid to be sealed. The mechanical seal 1301 according to the present embodiment is configured as a so-called tandem mechanical seal in which the rotating seal ring 20 and the stationary seal ring 30 on the atmosphere side, and the rotating seal ring 21 and the stationary seal ring 31 on the equipment interior side face in the same direction.

In FIG. 12 , the holders 9 described in the first embodiment are used for fixing the adapter 1305 to the seal cover 1303 by holders. However, the present invention is not limited to this. As holders, the configuration of the modifications A to M of the holders 9 according to the first embodiment described above may be applied. Needless to say, the shapes of the seal cover and the adapter are changed corresponding to the configuration of the holders to be applied.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments.

For example, in the embodiments described above, the holders are described as being inserted and fitted into the receiving recesses formed in the seal cover or into the receiving recesses formed by the seal cover and the flange portion of the adapter. There is no need to provide a receiving recess in the seal cover or in the flange portion of the adapter.

Further, holders are not limited to four holders equiangularly arranged, and a plurality of holders only needs to be arranged in the circumferential direction.

Further, the adapter may be fixed to the seal cover from the atmosphere side.

Further, the configuration for fixing the adapter by the holders described in the embodiments described above may be applied to a single mechanical seal.

REFERENCE SIGNS LIST

-   -   1 mechanical seal     -   2 rotary shaft     -   3 seal cover     -   3 f internally threaded hole (threaded hole)     -   4 sleeve     -   5 adapter     -   5 b flange portion     -   5 e first outer peripheral surface     -   5 f annular surface portion     -   5 g second outer peripheral surface     -   5 h annular stepped portion     -   7 squeeze packing     -   8 baffle     -   9 holder     -   9 a cylindrical portion     -   9 b flange portion (outer flange portion, contact portion)     -   9 c bottom portion (inner flange portion)     -   9 d through hole     -   9 e receiving recess     -   10 receiving recess     -   10 a bottom surface portion     -   10 b first side surface portion     -   10 c outer edge surface portion     -   10 d second side surface portion     -   11 bolt     -   11 a body part     -   11 b head part     -   20,21 rotating seal ring     -   20 a,21 a sliding surface     -   30,31 stationary seal ring     -   30 a,31 a sliding surface     -   60,61 bellows member 

The invention claimed is:
 1. A mechanical seal comprising: a rotating seal ring which rotate together with a rotary shaft; a stationary seal ring, an adapter which holds the stationary seal ring, the adapter being fixed to a seal cover by bolts; and a plurality of holders provided with through holes, a body part of each of the bolts passing through each of the through holes and being screwed into each of threaded holes formed in the seal cover, the plurality of holders being arranged so as to surround the rotary shaft and brought into contact with the adapter in axial directions of the bolts, the adapter has an annular flange portion protruded in an outward radial direction and brought into contact with the seal cover in the axial direction, the holders have inner flange portions formed around the through holes, each of the inner flange portions having a first end surface brought into contact with each of bottom portions of head parts of the bolts and a second end surface brought into contact with the seal cover or the annular flange portion of the adapter, the first end face and the second end face being opposed to each other in the axial direction, the inner flange portion of each of the holders is pressed toward the seal cover by screwing the bolts into threaded holes and as a result the adapter is fixed to the seal cover though the holders.
 2. The mechanical seal according to claim 1, wherein contact portions of the holders with the adapter are outer flange portions formed in the holders so as to extend radially outward.
 3. The mechanical seal according to claim 1, wherein the holders are provided with receiving recesses for receiving the head parts of the bolts.
 4. The mechanical seal according to claim 1, wherein the seal cover is provided with receiving recesses for receiving the holders.
 5. The mechanical seal according to claim 4, wherein each of the holders and each of the receiving recesses in the seal cover are formed in a circular shape as viewed in a screw insertion direction of the bolts and are fitted to each other.
 6. The mechanical seal according to claim 4, wherein each of the holders and each of the receiving recesses in the seal cover are formed in a non-circular shape as viewed in a screw insertion direction of the bolts and are fitted to each other.
 7. The mechanical seal according to claim 2, wherein the adapter has portions interposed between radially inner side parts of the outer flange portions and the seal cover, gaps are formed between radially outer side parts of the outer flange portions and the seal cover.
 8. The mechanical seal according to claim 1, wherein a squeeze packing is provided so as to be at least partially positioned between the holders and the seal cover in the screw insertion direction of the bolts.
 9. The mechanical seal according to claim 3, wherein the adapter has portions interposed between radially inner side parts of the outer flange portions and the seal cover, gaps are formed between radially outer side parts of the outer flange portions and the seal cover. 